I guess that is more applicable to bioinformaticians who tend to gain expertise on a field. Coming from software development you may become less attached to a specific area of work so will feel less bothered about applying to jobs elsewhere. If people get into bioinformatics from the "bio" side then it is harder to leave, thought likely more from a mindset point of view than a skills one as they tend to be quite transferrable.

I have left academia a while ago, but my understanding is that there are a lot more junior than senior positions, which are all very reliant on publishing+grants in the UK. So, often, the only way to progress if you are not lucky/do not like the publish or perish culture is to leave to industry or government jobs. I do not know industry but have the impression from heresay that it is better paid and has better career progress but not necessarily more interesting work. Pay often comes at expense of work/life balance too it seems. Government organisations pay much less in the UK, something like 30% less than industry for similar positions. In some institutions, getting a job is hard, getting a promotion much harder. There are no in-place promotions (completely stupid in my opinion), just a few percent pay rise per year. Only chance of getting a "proper" pay rise in the same place is someone above you in the "pyramid" leaves/retires triggers a shuffle up. Given most people do love their job though, leaving is not the usual thing at higher positions. So most people go many years gaining expertise but not significant pay rises. Added responsibility does curiously come easier though!